I Love You.
In My family I sometimes say I love you. I want to say that phrase to them with out it sounding wrong in the since of me saying this to my wife. (I'm not married). 
3 Answers
Te quiero papá - for your father
Te amo mamá - for your mother
Te amo hija - for your daughter
Te amo hijo - for your son
Te quiero abuelo - for your grandfather
Te quiero abuela - for your grandmother
Te quiero tío - for your uncle
Te quiero tía - for your aunt
Te amo primo - for your cousin
Te quiero hermano - for your brother
Te amo hermana - for your sister
Te amo al prójimo - for your neighbor
Te amo mujer - for your wife
Te amo novia - for your girlfriend
You happened to say you weren't married.....here is a helpful little sentence that is accompanied by a ring----
¿Quieres casarte conmigo? Will you marry me?
"Te amo" is has a stronger meaning than "Te quiero". You can say both to your family. It's up to you but I wouldn't say te amo to my cousin as lola suggested...
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I say te amo to my wife/husband, kids, my mom and dad. For the rest of the family, friends, neighbor, etc. I say te quiero 
